Display device

Abstract

There is disclosed a display device which is driven by a two-field drive scheme. That is, brightness corresponding to one frame of image is obtained in two scans. The display screen is divided into plural regions. One of the regions is driven by a black insertion method. The other region is driven by a pseudo-normal drive method. In this method, an image based on the same display data is displayed twice. The display data is converted such that the gamma characteristics of the pseudo-normally driven region are substantially equal to the gamma characteristics of the region driven by the black insertion method. If necessary, each individual pixel in the boundary region between the region driven by the black insertion method and the region driven by the pseudo-normal drive method is displayed black or white. The boundary region has a width of at least two pixels.

1 . A display device for producing brightness corresponding to an externally applied video signal, wherein
 (A) the display device can operate in a first mode in which a display area is divided into plural regions and the video signal is displayed and in a second mode in which the video signal is displayed without dividing the display area,   (B) in said first mode, the video signal that is singular is displayed over the whole display area,   (C) one frame period in which an amount of the video signal corresponding to one frame of image is displayed is divided into plural field periods,   (D) in each of the field periods, an amount of the video signal corresponding to one frame of image is displayed,   (E) in said first mode, (i) the video signal is displayed on one of the regions at a brightness level higher than a brightness level corresponding to the externally applied video signal during one of the field periods, (ii) the video signal is displayed on other one of the regions at a brightness level lower than the brightness level corresponding to the externally applied video signal during one of the field periods, and (iii) the video signal is displayed on other one of the regions at the brightness level corresponding to the externally applied video signal during one and other one of the field periods, and   (F) in said second mode, (i) the video signal is displayed at a brightness level higher than the brightness level corresponding to the externally applied video signal during one of the field periods and (ii) the video signal is displayed at a brightness level lower than the brightness level corresponding to the externally applied video signal during other one of the field periods or the video signal is displayed at the brightness level corresponding to the externally applied video signal during one and other one of the field periods.   
   
   
       2 . A display device as set forth in  claim 1 ,
 wherein said externally applied video signal is displayed at a brightness level higher than the brightness level corresponding to the video signal during one of said field periods, and   wherein a difference between a gamma value used when the video signal is displayed at a brightness level lower than the brightness level corresponding to the externally applied video signal during other one of the field periods and a gamma value used when the video signal is displayed at the brightness level corresponding to the externally applied video signal during one and other one of the field periods is set to less than a given value.   
   
   
       3 . A display device as set forth in  claim 1 , wherein a boundary region between said plural regions is displayed at a maximum or minimum brightness level. 
   
   
       4 . A display device as set forth in  claim 1 , wherein mode of operation of the display device is switched between said first mode and said second mode in response to a control signal applied from outside. 
   
   
       5 . A display device as set forth in  claim 1 , wherein said display area is divided in a horizontal direction in said first mode. 
   
   
       6 . A display device as set forth in  claim 1 , further including:
 a display panel on which plural pixels are arranged;   a memory capable of storing an amount of said externally applied video signal which corresponds to one or more frames of image;   a control circuit for controlling writing and reading of said video signal into and from said memory;   a conversion circuit for converting said video signal read from the memory;   a data driver for supplying a grayscale voltage corresponding to the converted video signal to said display panel; and   a scanning driver for selecting ones of said pixels to which said grayscale voltage is to be applied;   wherein said control circuit reads said video signal from the memory repeatedly a number of times corresponding to the number of the field periods at timings corresponding to the field periods; and   wherein in said first mode, said conversion circuit (i) converts said video signal, which corresponds to one of said plural regions and has been read out at a timing corresponding to one of the field periods, into a brightness level higher than the brightness level corresponding to the externally applied video signal and (ii) converts said video signal, which corresponds to one of said plural regions and has been read out at a timing corresponding to other one of the field periods, into a brightness level lower than the brightness level corresponding to the externally applied video signal.   
   
   
       7 . A display device for producing brightness corresponding to an externally applied video signal, said display device comprising:
 a display area divided into plural regions;   wherein said video signal that is singular is displayed over the whole display area;   wherein one frame period in which an amount of the video signal corresponding to one frame of image is displayed is divided into plural field periods;   wherein in each of the field periods, an amount of the video signal corresponding to one frame of image is displayed;   wherein (i) the video signal is displayed on one of the regions at a brightness level higher than a brightness level corresponding to the externally applied video signal during one of the field periods, (ii) the video signal is displayed at a brightness level lower than the brightness level corresponding to the externally applied video signal during other one of the field periods, and (iii) the video signal is displayed on other one of the regions at the brightness level corresponding to the externally applied video signal during one and other one of the field periods; and   wherein a difference between a gamma value used when the video signal is displayed on one of the regions and a gamma value used when the video signal is displayed on other one of the regions is set to less than a given value.   
   
   
       8 . A display device as set forth in  claim 7 , wherein gamma characteristics used when the video signal is displayed on one of the regions and gamma characteristics used when the video signal is displayed on other one of the regions are made uniform. 
   
   
       9 . A display device as set forth in  claim 7 , wherein a boundary region between said plural regions is displayed at a maximum or minimum brightness level. 
   
   
       10 . A display device as set forth in  claim 7 , further including:
 a display panel on which plural pixels are arranged;   a memory capable of storing an amount of said externally applied video signal which corresponds to one or more frames of image;   a control circuit for controlling writing and reading of said video signal into and from said memory;   a conversion circuit for converting said video signal read from the memory;   a data driver for supplying a grayscale voltage corresponding to the converted video signal to said display panel; and   a scanning driver for selecting ones of said pixels to which said grayscale voltage is to be applied;   wherein said control circuit reads said video signal from the memory repeatedly a number of times corresponding to the number of the field periods at timings corresponding to the field periods; and   wherein said conversion circuit (i) converts said video signal, which corresponds to one of said plural regions and has been read out at a timing corresponding to one of the field periods, into a brightness level higher than the brightness level corresponding to the externally applied video signal and based on a gamma value used when the video signal is displayed on one of the regions and (ii) converts said video signal, which corresponds to one of said plural regions and has been read out at a timing corresponding to other one of the field periods, into a brightness level lower than the brightness level corresponding to the externally applied video signal and based on the gamma value used when the video signal is displayed on the one of the regions.   
   
   
       11 . A display device for producing brightness corresponding to an externally applied video signal, said display device comprising:
 a display area divided into plural regions;   wherein said video signal that is singular is displayed over the whole display area;   wherein one frame period in which an amount of the video signal corresponding to one frame of image is displayed is divided into plural field periods;   wherein in each of the field periods, an amount of the video signal corresponding to one frame of image is displayed;   wherein (i) the video signal is displayed on one of the regions at a brightness level higher than a brightness level corresponding to the externally applied video signal during one of the field periods, (ii) the video signal is displayed at a brightness level lower than the brightness level corresponding to the externally applied video signal during other one of the field periods, and (iii) the video signal is displayed on other one of the regions at the brightness level corresponding to the externally applied video signal during one and other one of the field periods; and   wherein a boundary region between said plural regions is displayed at a given brightness level irrespective of said externally applied video signal.   
   
   
       12 . A display device as set forth in  claim 11 , wherein said given brightness level is a maximum or minimum brightness level. 
   
   
       13 . A display device as set forth in  claim 11 , wherein said boundary region has a width of two or more pixels. 
   
   
       14 . A display device as set forth in  claim 11 , further including:
 a display panel on which plural pixels are arranged;   a memory capable of storing an amount of said externally applied video signal which corresponds to one or more frames of image;   a control circuit for controlling writing and reading of said video signal into and from said memory;   a conversion circuit for converting said video signal read from the memory;   a data driver for supplying a grayscale voltage corresponding to the converted video signal to said display panel; and   a scanning driver for selecting ones of said pixels to which said grayscale voltage is to be applied;   wherein said control circuit reads said video signal from the memory repeatedly a number of times corresponding to the number of the field periods at timings corresponding to the field periods; and   wherein said conversion circuit (i) converts said video signal, which corresponds to one of said plural regions and has been read out at a timing corresponding to one of the field periods, into a brightness level higher than the brightness level corresponding to the externally applied video signal, (ii) converts said video signal, which corresponds to said boundary region and has been read out at a timing corresponding to one of the field periods, into said given brightness level, (iii) converts said video signal, which corresponds to the boundary region and has been read out at a timing corresponding to other one of the field periods, into said given brightness level, and (iv) converts said video signal, which corresponds to one of said plural regions and has been read out at a timing corresponding to other one of the field periods, into a brightness level lower than the brightness level corresponding to the externally applied video signal.   
   
   
       15 . A display device for producing brightness corresponding to an externally applied video signal, said display device comprising:
 a display panel on which plural pixels are arranged;   a memory capable of storing an amount of said video signal which corresponds to one or more frames of image;   a control circuit for controlling writing and reading of said video signal into and from said memory;   a conversion circuit for converting said video signal read from the memory;   a data driver for supplying a grayscale voltage corresponding to the converted video signal to said display panel; and   a scanning driver for selecting ones of said pixels to which said grayscale voltage is to be applied;   wherein a display area of said display panel is divided into plural regions;   wherein said video signal that is singular is displayed over the whole display area;   wherein one frame period in which an amount of the video signal corresponding to one frame of image is displayed is divided into plural field periods;   wherein in each of the field periods, an amount of the video signal corresponding to one frame of image is displayed;   wherein (i) the video signal is displayed on one of the regions at a brightness level higher than a brightness level corresponding to the externally applied video signal during one of the field periods, (ii) the video signal is displayed at a brightness level lower than the brightness level corresponding to the externally applied video signal during other one of the field periods, and (iii) the video signal is displayed on other one of the regions at the brightness level corresponding to the externally applied video signal during one and other one of the field periods;   wherein said control circuit reads said video signal from said memory repeatedly a number of times corresponding to the number of the field periods at timings corresponding to the field periods; and   wherein said conversion circuit (i) converts said video signal, which corresponds to one of said plural regions and has been read out at a timing corresponding to one of the field periods, into a brightness level higher than the brightness level corresponding to the externally applied video signal and (ii) converts said video signal, which corresponds to one of said regions and has been read out at a timing corresponding to other one of the field periods, into a brightness level lower than the brightness level corresponding to the externally applied video signal.